The present invention relates to delay fuses for explosive shells or projectiles, and more particularly to impact delay fuses for such shells for delaying detonation until after impact of the shell with a target.
Various means have been used in prior art to improve the maximum effectiveness of a projectile warhead while maintaining safety and handling. In particular situations, it is advisable to delay detonation of the warhead for a short period of time after initial impact of the projectile with a target. For example, it is in some instances desired to delay detonation of the projectile until the projectile has either passed through the target impact medium, has ricocheted from the impact surface, has broached from the impact surface, or has come to rest in the impact medium. One such prior art device is described in U.S. Pat. No. 3,913,486 for An Automatic Delay Graze Sensitive Fuse which utilizes linear deceleration associated with the impact to cock and then release the firing pin for detonation of the explosive charge of the shell.
However, in some instances, the utilization of linear deceleration has not proven fully satisfactory in that such devices have not been capable of distinguishing between linear deceleration as a result of target penetration and linear deceleration as a result of tumbling of the projectile from the target. Consequently, such prior art projectiles have not always fired when intended. In addition, such linear deceleration initiation type devices have not always proven effective under graze impact situations.